Electric water-heater.



0. A. KNOPP.

ELECTRIC WATER HEATER.

APPLICATION FILED IuNE 7. IsIs.

Patented May 7,1918.

Ill-"li OTTO A. KNOPP, OF OAKLAND, CALIFORNIA..

ELECTRIC WATER-HEATER.

Specification of Letters Patent.

Application filed J une 7, 1916. 'Serial No. 102,223.

To all whom it may concern'.-

Be i-t knownthat I, OTTO A. KNOPP, a citizen of the United States, residin in the city of Oakland,-county .of Alame a, and Statef California, have made a new and usefulA invention-xto wit, Improvements in Electric Water-Heaters; and I do hereby declare the following to be a full, clear, concise, and exact description of the same.

Among the objects of this invention are to produce a thermostatic electric water heater of cheap and rugged construction without movable contacts and delicate resistance elements, so combined and arranged that the heater will automatically reduce its wattage 'as soon as the desired water temperature is reached.

In this specification and the annexed drawings I illustrate the invention in the form that I consider the best, but it is -to be' understood that I do not limit myself to this form because the invention may be embodied in other forms, and i't is also to be understood that in and by the claims following the description, I desire to cover the invention in Whatever form it may be embodied. In the accompanying one sheet of Adrawmgs: f

Figlire 1 is a diagrammatic side elevation of a circulatin reservoir of the kitchen boiler type having this invention applied thereto.

Fig. 2 is a longitudinal section of a water heater constructed in accordance with this invention.

Fig. 3\ is an enlarged fragmentary 'detail' of the automatic resilient controlmechanism for regulating the 'compression on the resistance pile forming the heating element in the water heater.

Some .of the particular advantages of this invention as hereinafter described are as follows: The wattage is the highest during the initial heating period when the water is cold, and will automatically decrease as the temperature of the water rises. This decrease in wattage can be graduated in accordance 4with the temperature of water desired b adjustin the automatic control, for examp e, when t e water has reachedatlie temperature of 1200 Fahrenheit, or at any other desired point, the wattage automatically decreases gradually from this point until the minimum is reached. Inversely the wattage will automatically rise again to -its maximum as soonV as any amount of hot Water is drawn from the boiler and replaced by cold water. 7Should the temperature of the water riseunduly high, due to impeded circulation or other causes, the wattage will Patented May 7, 1918.

be automatically cut down by the thermostatic action of Ithe heater which decreases the wattage, which in consequence decreases protectingthis element'l from an excessive temperature.

In detail k the drawings includes the boiler l as lgener.- ally used in domestic service, having the cold water inlet pipe 2 extending well down into the boiler to near the bottom thereof. The hot water is drawn from'the boiler through the service pipe 3 at the top thereof. The circulating system includes the cold water outlet 4 leading from the bottom of the boiler through the water heater and into the outlet pipe 5 connecting with the service pipe 3 'at or near the top of the boiler, whereby the thermo-Siphon effect produced by the water heater will cause the water within they boiler 1 to circulate, until the` whole body, reaches a uniform temperature, unless drawn oli' through the service pipe 3,

" in which event the hottest water from the top of the boiler is forced into the service pipe by the incoming cold water introduced into the bottom of the boiler; such arrangement with modifications to meet particular conditions being in accordance with common practice.

- the heat generated by the heating elementf' the construction illustrated in removable ring 9 bolted thereto and compressing the heater base 10 against the flange 11 formed on the casing, thus rendering the' casing pressure tight. To prevent radiation of heat from 'the heater, it is surrounded with any suitable heat insulating material, such as mineral wool 12 inclosed within the ornamental jacket 13.

The heating unit includes the cylindrical shell 14 preferablyof zinc or other material having a large temperature expansion coeliicient, flanged at thebottom and soldered or otherwise hermetically fixed to the base 10 and closed at the top by the annular bush' ing 15 fixed therein.

The heating element consists of a pile of "carbon disks 16,packed vertically on a'glass 23-23 threaded on the top of the conducting post 24, insulated from and hermetically sealed to the base 10 at the bottom, and oonnected to the other terminal wire 25 of the electric circuit. The elasticity of the conductor 22 permitsof the expansion of the carbon disk pile in its separations.

The resistance' and wattage consumption is regulatedby varying the compression on the pile of carbon disks. This is accom plished by the knurled nut 26 threaded into the bushing 15, and having a sleeve 27 fixed therein and inclosing a section of glass tube 28 yresting on the contact 21 on top of the pile. Screwing down the nut 26 causes the yglass tubeto force thedisks of the pile into closer contact increasing the wattage and in# creasing the heat generated in the pile. The

,reverse action of the nut 26 having a reverse effect on the resistance. In this manner the normal resistance of the pile can be fixed in accordance with the desired amount of heat to be generated in the pile, when the fusv -current is first turned on and the surrounding water is cold. The shell 14 is entirely filled with oil or some suitable nonelectrolytic liquid.

So far as I am aware, I am the rst to-- surround or submerge such a resistance or compression heating element in oil or a nonelectrolytic liquid.v Such submersion results in greater uniformity in the action of the pile, higher eliiciency, greater durability, more rapid dissipation of heat therefrom and other electrical and mechanical advantages. The film of oil between the disks forming the pile, prevents arcing and sparkingtherebet-ween, insures the positive and uniform separation between each and all of the disks under variation of mechanical pressure on the pile; whereas a pile of dry disksl do not Separate uniformly, or stick together in groups and others separating proportionately too far apart, set up arcing and sparking that breaks down the opposed surfaces of the disks, destroying thelr usefulness and interfering with the uniform resistance of the pile as a whole, generating'an overproduction of heat at a concentrated point when the generation of heat should be uniform throughout the pile.

fIn the present instance, oil is particularly valuable as a dissipating agent conducting `theheat from the pile to the shell 14, that inturn radiates the heat to the water passning through the casing 6. The shell 14 re- -hot water is drawn off through the service pipe 3, permitting a like quantity of cold water to enter through the inlet pipe 2, which discharges near Athe bottom of the boilerreplacing the hot water drawn from the casing 6, cooling the shell 14, causing it to contract and compress the resistance, proportionately increasing the heat output therefrom until the high temperature of the water is again restored. Each variation of temperature in the body of'water causes a consistent variation in the heat generated and transmited to the.water by the heating unit.-

There are instances where it is desirable,- to maintain the maximum wattage 0f the heater until a certain temperature of water is reached, for instance, vone hundred and twenty degrees. This is-easily accomplished by introducing a resilient element between the adjusting nut and the top of the heating element, whereby a certain proportion of the expansion of the shell 14 is compensated for by the contra-expansion in the vresilient element, until the'resilient element is overcome and the expansion of the shellv 14 acts directly on the heating element. A convenient means for accomplishing this object is illustrated in Fig. 3, in which the adjustable knurled nut 26 is threaded into a similarly adjustable annular nut 29 threaded in the bushing 15 and having an inturned annular iange 30, clearing the -diameter of the sleeve 27 which has an overhanging annular shoulder 31 adapted to engage the inturned flange 30. The calibrated spring 32 is.c0mpressed between the shoulder 31 and the end of the adjusting nut 26 by the cap 33 threaded on the end ofthe sleeve 27 and bearing against the inturned 'ange 34 onV the adjusting nut 26. The cap 33 is provided with a screw driver `Slot 33" reached by removing the screw plug 35 in the .top of the nut 26. By this arrangement the spring 32 can be adjusted to resist the expansion of the carbon pile with any desired initial tension. The tension of izo leased is regulated byl adjusting the nut 26' against the tension of the spring 32.

Having thus described my invention, what I claim and desire to secure by Letters Patent is 1. An electric water heater including an inclosing expansive shell; a heating element in said shell; and means for varying the wattage of said element by the expansion and contraction of said shell.

2. An electric water heater including an inclosing expansive shell, a heating element in said shell; and a liquid in said shell submerging said element and means for varying the wattage of said element by the expansion and contraction of said shell.

3. An electric'water heater including an inclosing casing'` having inlet :and outlet openings; a hermetically sealed expansive .y shell in said casing; a thermostatic heating element in said shell; and means' for varying the wattage of said element by the expansihon and contraction ofsaid shell.

4. An electric water heater including an inclosing casing having inlet and outlet openings; a hermetically sealed expansive shell in said casing; a sectional heating element in said shell and compressed thereby, whereby the expansion of said shell releases the compression on said element.

5. An electric water heater including an inclosing casing having inlet and outlet openings; a hermetically seated shell in said casing; a thermostatic heating element in said shell, and a liquid in said shell.

6. An electric water heater including an inclosing casing having inlet and outlet openings; a hermetically sealed shell in said casing; a compression heating element in said shell; and means in said shell for varying the compression on said element.

7. An electric water heater including an inclosing expansion shell; a compression heating element in said shell, and a resilient compression means interposed between said shell and said heating element.

8. An electric water heater including an inclosing expansive shell; a compression heating element in said shell; an adjustable compression means interposed between said shell and said heating element, and a resilient member interposed in said compression means.

f In testimony whereof, I have hereunto set myv hand at San Francisco, California, this 24th day of May, 1916.

OTTO A. KNOPP. In presence of- BALDWIN VALE,

A.. J'. HENRY. 

